Esters of substituted acetic acids



Patented June 6, 194

ESTERS OF SUBSTITUTED ACETIC ACIDS Donald J. Loder, Wilmington, and Wilber O. Teeters, Roselle, Del., assignors to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Original application May 6, 1-939,

Serial No. 272,134. Divided and this application January 25, 1940, Serial No. 315,524

11 Claims.

The present invention relates to new materials and to methods for their preparation, and more particularly, to the alkoxy and alkoxy methylene substituted acetic acids and methods for their preparation. The application is a division of' our copending appli cation S. N. 272,134, filed May 6, 1939.

An object of the present invention is to provide new compositions of matter and processes for their preparation. A further object of the invention is to provide monoand poly-ethylene glycol and monoand di-glycerol and triglyceryl esters of substituted glycolic acids, together with processes for their preparation. Yet another object of the invention is to provide a process for the preparation of glycol monoand di-glycolates and glycerol monoand di-glycolates by esterifying substituted glycolic acid with glycols and glycerol, respectively. A further object of the invention is to provide a process for the preparation of glycol glycolates, glycerol glycolates, or a glyceryl glycolate which comprises reacting a glycolide with glycolsor glycerol. Other objects and advantages of the invention will hereinafter appear.

These objects, as Well as others which will be apparent as the description proceeds, may be accomplished by reacting a lower alkyl ester of any oxy-substituted acetic acid with a polyhydric alcohol under conditions favorable to the interchange of alcohol radicals. This interchange of alcohol radicals is efiected by heating the alcohol and ester together, preferably in the presence of alkaline alcoholysis catalysts. The ester interchange proceeds more readily if the alcohol selected for reaction with the ester boils at a higher temperature than the alcohol liberated by the interchange, because the latter alcohol is then more readily removed from the zone of reaction, for example, by distillation.

The ester interchange process described above may be employed for the preparation of either the monoglycolates or the polyglycolates, for example, When it is desired to prepare ethylene glycol monoglycolate, in accord with the ester interchange process, equimolecular proportions of the ester and ethylene glycol are reacted. If, on the other hand, the reaction mixture contains two moles of the ester per mole of the ethylene glycol and the reaction continues to completion, the product will be ethylene glycol diglycolate. In like manner, if it is desired to obtain a glycerol monoand di-glycolate or glyceryl triglycolate, one mole of glycerol is reacted With one, two, or three moles of an ester of glycolic acid. The procpolyhydric alcohol esters of I ess is applicable generally to the preparation of polyhydric alcohol, mono and poly-glycolates, monoand poly-alkoxy glycolates and monoand poly-akoxy methoxy glycolates from the polyhydric alcohols and the lower alkyl esters of, re-

CHzKOCI-IzOCHs) COOH The methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, etc. esters of these acids, may be reacted with the polyhydric alcohols generally, such, for example, as: the glycols, e. g., ethylene glycol, propylene glycol, butylene glycol, amylene glycol, diethylene glycoLtrimethylene glycol, octadecanediol, tetramethylene glycol, hexamethylene glycol, or-thealcohols containing more than two hydroxyl groups, such as glycerol, diglycerol, triglycerol, trimethylol methane and trimethylol propane; sugars, such as, dextrose, sucrose, Xylose, galactose, fructose, maltose, and mannose; and the sugar alcohols, such as, sorbitol, mannitol, and dulcitol; as wellas; castor oil (glyceryl triricinoleate), hydrogenated castor oil, (hydroxy stearin) and like long chain polyhydric alcohols.

This invention likewise includes esters of glycolic acid, alkoxyand alkoxy methoxy-acetic acids-With ether alcohols, i. e., polyhydric alcohols having at least one free hydroxyl group, one or more hydroxyl groups being etherifi'ed. Examples of such ether alcohols include the monoalkyl ethers of ethylene glycol, such as the monomethyl, -ethyl, -Propyl or -buty1 ethers of ethylene glycol, propylene glycol, etc. Esters of this classwould be, e. g., ethylene glycol monomethyl ether glycolate, ethylene glycol monoethyl ether glycolate, ethylene glycol monomethyl ether methoxy acetate, CH2 OCH3)COOCH2CH2OCH3 and ethylene glycol monomethyl ether methoxy methoxy acetate,

CH2(OCH2OCH3) ooocmcn'zoona The mono and di-glycolates of the monoglycerides are likewise included, e. g., the monoglycolates of the monoglycerides,

CH2( OH) COOCH'zCHOI-LCHzzOOCR Polyhydric alcohol esters as well as ether alco- CH2(OR) COOH e. g. ethoxy, propoxy, isobutoxy-acetic acids, etc.;

the alkoxy alkoxy acetic acids,

CH2 OROR) COOH e. g., ethoxy methoxy-, propoxy methoxy-, isobutoxy methoxy-acetic acids, etc; and the alkoxy carbomethoxy methoxy acetic acids,

CH2(OCH2OCH2COOR) COOH e. g., methoxy carbomethoxy methoxy acetic acid or ethoxy carbomethoxy methoxy acetic acid,

whichmay be prepared by reacting glycolic acid formals with carbon monoxide in accord with the process described in U. S. Patent 2,250,487 of July 29, 1941, or in accord with the process of U. S. Patent 2,316,605 of April 13, 1943.

The esters of the present inventionare preferably prepared by the above described ester interchange process, for the reason that this proc-' ess provides a means of obtaining'both the monoand poly-glycolates in excellent purity and yield. Simple esterification may be employed, however, that is, by the interaction of the polyhydric alcohol with the glycolic acid. There appears to be one exception to this, in that, due to the dehydrating characteristics of glycolic acid, it does not react readily with glycerol but forms acrolein at the expense of the glycerol ester and, consequently, simple'esterification should preferably not be employed when the glycerol esters of glycolic acid are desired.

The invention likewise provides another ester interchange process for the preparation of esters of glycolic acid. This process involves the inter-' action of a polyhydric alcohol or ether alcohol with glycolide, which may be considered to be a poly-ester of glycolic acid. This reaction may be effected by first forming the glycolide (prepared, e. g.,' in the usual manner by heating the glycolic acid to'drive off all the water), and subsequently reacting the glycolide (which may be present as a diglycolide, or as a polyglycolide) with the polyhydric alcohol. If a partially dehydrated glycolic acid is used, e.-g., a diglycolide or polyglycolide in the presence offree glycolic acid, the initial reaction is carried out under reflux and. then water of esterification, of free glycolic acid and glycol removed with the aid of heat, either with or without a water carrier, such as, toluene. Ordinarily, this ester interchange may be conducted under atmospheric pressure,

particularly with the higher boiling polyhydric alcohols, although if low boiling alcohols are employed, autogenous pressure or applied pressures of from 5 to 600 atmospheres may be employed. The more detailed practice of the invention is illustrated by the following examples in which parts given are by weight unless otherwise stated. There are, of course, many forms of the invention other than these specific embodiments.

EXAMPLE I.-ETHYLENE GLYcoL MONOGLY COLATE V (A) To 2250 parts (25 moles). of methyl glysodium methoxide solution). This mixture was refluxed under a iractionating column, fitted with a distilling head arranged for controlled reflux, until the head temperature had receded to 64-65 C. The methanol was removed as rapidly as possible at the head of the column, the head temperature being carefully maintained between 64" C. and 66 C. The refluxing and the collecting of the methanol were continued for approximately ten hours, at the end of which time approximately 800 grams (25 moles) of methanol had been collected.

, The heat was discontinued and any low boiling material which remained was removed by vacuum distillation. (If desired the color of the product may be improved by treatment with 2 1 per cent. of its'weight of a standard decoloriz- --ing charcoal. For most purposes, however, the

; Yield quantitative color of the untreated ester was satisfactory).

(13) To 310 parts (5 moles) of ethylene glycol, contained in a suitable 3-necked flask equipped with an efiicient stirrer and reflux condenser, was added 290 parts (5 moles) of powdered polyglycolide, prepared by completely dehydrating glycolic acid at elevated temperatures (-220 (3.). The temperatture of the reaction mixture was raised toand held at a temperature of 100- 200, preferably between 200 C., for a period of approximately five hours.

In'both (A) and (B) the reaction mixture was cooled, and the product obtained was a pale amber-colored'liquid which contained 98 to 99 per cent; of glycol monoglycolate. The yield was substantially quantitative, based on either the glycol or glycolate; sp. gr. was 1.283 60 F./60 F. and the saponification number was 460.

EXAMPLE II.-ETHYLENE DIGLYCOLATE The conditions and procedure are the same as Amber colored viscous liquid Sp. gr. 1.327/20/4. Sap. No. 611.

EXAMPLE IIL-GLYCEROL MONOGLYCOLATE The conditions and procedure are the same as Example I.

i Quantities Product Yield quantitative Pale amber colored liquid. Sp. gr. 1.320 60/60 F. Sap. No. 380.

EXAMPLE IV-GLYCEROL DIGLYCOLATE The conditions and procedure are the same as for Example I.

Quantities (A) Glycerol monoglycolate (in Example III) 1950 parts; 13 moles Methyl glycolate 1170 parts, 13 moles Anhydrous potassium carbonate (catalyst) 10 parts Methanol 01f 1 416 parts, 13 moles (B) Glycerol (96%) 1245 parts, 13 moles Methyl glycolate 2340 parts, 26 moles Catalyst:

1 g. Na in g. of methanol Anhydrous potassium carbonate 5 g. Methanol ofi" 832 parts, 26 moles Products from (A) and (B) are identical in constants.

Yield substantially quantitative in both cases. Amber colored viscous liquid.

Sp. gr. 1.393 20/4.

Sap. No. 542.

EXAMPLE V.BETA-ETHOXY ETHYL GLYCOLATE Up to and'through the removal of methanol the conditions are the same as Example I.

Quantities Methyl glycolate Beta-ethoxy ethanol 990 parts, 11 moles (Cellosolve) 900 parts, moles Catalyst:

1 part Na in 4 parts of methanol Anhydrous potassium carbonate 5 parts Methanol voff 309 parts, 9.7 moles The refluxing and the collecting of the methanol were continued until no more methanol-was C1120 mm; Sap. No.: theoretical 378; found 375.

EXAMPLE VI.BETAMETHOXY Emu. GLYCOLA'llE To a mixture of 760 line glycolic acid and 760 parts (10 moles) of (Water carrier). ed to reflux temperature and the water of esterification, which separated as a lower layer in a suitable decanting type distilling head, was rea yield of '70 to 80%. It was recovered as a mobile, colorless liquid having a'B. P. of l55-156/1 35 mm.; a sp. gr. of 1.163 60'/60 'F; and a saponification number of 417. EXAMPLE VII.OCTADECANEDIOL DIGLYcoL'A'rE The procedure was the same as in Example I column, at 105-l10; the reaction mixture was blanketed with nitrogen and a slow stream of this gas was continuously passedover the surface dur The reaction mixture was heat:

1 Ethylene gl-yco ing the ester interchange; the pot temperature was held between 160-170 throughout the'reaction; the product was filtered hot to givea' quantitative yield of the ester.

Quantities Octadecanediol 429 parts, 1.5 moles Isbutyl glycolate 396 parts, 3.0 moles Sodium methoxide (30%) (catalyst) 6 parts Product White low melting solid Sap. No. theoretical 194; found 184.

EXAMPLE VIII.CASTOR OIL GLYCOLATE' Procedure the same as for octadecanediol die glycolate, Example VII.

Quantities Castor oil Isobutyl glycolate Sodium methoxide (catalyst) 3.0 parts of 30% in methanol Product Yield substantially quantitative. Amber reddish viscous liquid. Sap. No. 242.

EXAMPLE IX.ETHYLENE GLYcoL Mono- METHOXY ACETATE 888 parts. 1 mole 396 parts, 3 moles Yield substantially quantitative.

' Colorless liquid.

B. P. 141-142 C./25 mm. Sp. gr. 1.174 60/50 F. Sap. No. 420.

. EXAMPLE -X.E 'rHYLEN BIS-METHOXY ACETATE Procedure same as for Example IX.

' Quantities Methyl methoxy acetate 520 parts,-5.0 moles parts, 2.5 moles Sodium methoxide (catalyst) (3mm methanol) was.

Product Yield substantial-1yquantitative. V

Colorless liquid. B. P. 176-77" C./25 mm. Sp. gr. 1.194 60/60 F. Sap. No. 555.

In place of the sodium methoxide 0f the examples, other alcoholysis catalysts may be used suchas sodium ethoxide, sodium glyceroxide, and"-al-- kalime'tal alkoxidesgenerally; sodium hydroxide, anhydrous potassium carbonate, calcium oxide,

litharge, etc.;. or mixtures of the two types.- Alkaline alcoholys'is catalysts are, in general, more satisfactory, though in some instances; acid alco holysis catalysts, e. g., sulfuric, p. toluene su1-'- g phonic acid, and hydrochloric acids, maybe employed. 1

2. parts The polyhydric alcohol esters and ether-esters ofglycolic acid, as well as the other esters described herein, have many characteristics which particularly fit them for uses in the arts. They are all generally useful as solvents. or plasticizers for many natural and synthetic resins which are used with or without pigments, fillers, extenders and the like, which compositions are employed for the preparation of lacquers, pigments, paste pigments, etc., or for the formation of films, filaments, rods, tubes, or shaped articles. More specifically, they are generally useful as solvents, plasticizers and softeners for natural resins, such, for example, as Damar, Copal, Kuri and for the synthetic resins such, for example, as the alkyds; cumarone-indene; chlorinated diphenyl; soluble types of polymerized hydrocarbons, phenol-formaldehyde and urea-formaldehyde resins; ester gum; polymeric acrylic and methacrylic acids and their esters, amides, nitriles, imides, salts, interpolymers, and other derivatives; polyvinyl alcohol; the polyvinyl esters; styrene and other polymeric resins, as well as simple mixtures of the natural and/or synthetic resins, and/or interpolymers of the polymeric resins. The polyhydroxy alcohol esters of glycolic acid are also useful as solvents, plasticizers or softeners of regenerated cellulose and the cellulose derivatives, such as,'cellulose acetate, nitrate, aceto-nitrate, aceto-propionate, methyl cellulose, ethyl cellulose and other organic derivatives of cellulose or mixtures thereof.

The polyhydric alcohol esters of glycolic acid are likewise generally applicable as the major ingredients in the preparation of printing pads and ink feeders'of all types, as penetrating agents for printing pastes, and as major ingredients in the preparation of inks, both for the printing of paper, textiles, wood, metal or other materials.

The ethylene glycol mono glycolate, diglycolate and glycerol mono-, diand tri-glycolate, may be used as softeners for glassine paper, as a substitute for glycerine in tobacco, as a softener for regenerated cellulose and as a substitute for glycerol in printing ink compositions. They have likewise been found acceptable for the sizing of the artificial and natural silks and particularly for the sizing of regenerated cellulose filaments and fabrics and are also most effective as softening agents for cotton, wool, linen, jute, rayon and silk.

Glycolate esters of the alkyl ethers of polyhydric alcohols such, for example, as glycolic acid esters of the monoalkyl ethers of ethylene glycol, HOCI-IzCOOCHzCI-IzOR, are, as has been generally stated above, excellent solvents for cellulose ethers and cellulose esters. These compositions are especially valuable in brush-type lacquers and lacquers applied hot, as they improve the flow and gloss properties of the resulting fihns. The ether-esters have been found acceptable as froth ing agents for the flotati n of ores and as solvents for the absorption of acidic gases such as the sulfur oxides, hydrogen sulfides, etc. Furthermore, they, together with the other polyhydric alcohol esters of glycolic acid, are excellent solvents and liquid media and pigments wherein they may be substituted for the ethers of the polyhydric alcohols.

Thev polyhydric alcohol esters and ether-esters of glycolic. acids, hereinbefore described, may also be used as ingredients in the preparation of compounds fordefrosting and anti-misting; in cosmetic preparations; fas dye solvents for basic acid and direct d es: as

for certain dyestuffs the fluid medium of electrolytic condensers; as ingredients in leather finishes and varnish removers; as solvents and fixatives for perfumes; as softeners for cork binders, glue, gelatin, paper and textile" sizes; as an ingredient in dentifrice compositions; as softeners for casein, zein, soybean, protein plastics, etc.; as an ingredient in leakproofing compositions for gas distributing systems, gas masks and the like; in the preparation of wetting, dispersing and penetrating agents, etc., such as sulfates and the like; as precipitation inhibitors; and as ingredients in fluids for hydraulically actuated mechanisms.

The phosphatederivatives of the polyhydric alcohol glycolates are likewise useful as plasticizers generally for use in combination with the aforementioned natural and synthetic resins, as well as the cellulose ethers, esters, and regenerated forms of cellulose.

The esters of the alkoxy acetic acids, in addition to the uses above described for the glycolic esters of the alkyl ethers of the polyhydric alcohols and because of their large number of active solvent groups, are particularly excellent solvents for gases, liquids, solids and resins. The excellent solvent properties of materials of this type can be attributed to the combination of ether and ester groupings.

All glycolate esters disclosed can be reacted with an aliphatic or aromatic anhydride or acid to give relatively water insoluble esters that are good plasticizer-softeners. As an example the glycerol glycolates reacted with acetic anhydride will give the triacetates of the three glycolates of glycerol.

From a consideration of the above specification it will be realized that many changes may be made in the details therein given without departing from the scope of the invention or sacrificing any of the advantages that may be derived therefrom.

We claim:

1. A process which comprises alcoholysis of an ester of a substituted acetic acid, having the formula CH2(OCH2Y) COOH, in which Y is selected from the group consisting of hydrogen and alkoxy groups, with a compound selected from the group consisting of polyhydric alcohols and alkyl ethers thereof, the compound of the group boiling higher than the alcohol whose radical forms a part of the ester.

2. A process which comprises alcoholysis of a substituted acetic acid ester of a lower aliphatic alcohol having the formula CH2(OCH2Y)COOX, in which Y is selected from the group consisting of hydrogen and alkoxy groups, and X is an alkyl group, with an alcohol selected from the group consisting of polyhydric alcohols and alkyl ethers thereof, the compound of the group boiling higher than the alcohol Whose radical forms a part of the ester.

3. A process which comprises the alcoholysis of an alkoxy acetate, CH2(OR) COOR in which R. is an alkyl group in each instance, with a polyhydric alcohol to form a polyhydric alcohol ester of the alkoxy acetic acid.

4. A process which comprises the alcoholysis of an alkoxy acetate, CH2 OR COOR in which R. is an alkyl group in each instance, with ethylene glycol, to form an ethylene glycol ester of the alkoxy acetic acid.

5. A process which comprises the alcoholysis of an alkyl alkoxy acetate with a polyhydric alcohol. 6. A process which comprises the alcoholysis of methylmethoxy acetate, CH2(OCH3)COOCH3,

with ethylene glycol to form an methoxy acetate.

7. A process which comprises the preparation of ethylene glycol monoalkoxy acetate,

CH2(OR) COOCHzCI-IzOH CH1OOC(OR) OH:

CH2OOC(OR)OH ethylene glycol in which Rs are alkyl groups, which comprises the alcoholysis of a mixture containing substantially two moles of an alkyl alkoxy acetate and one mole of ethylene glycol.

9. Ethylene glycol monomethoxy acetate,

HOCH2CH2OOC(CH3O) CH2 10. A methoxy acetic acid ester of a polyhydric alcohol.

11. A mono (methoxy-substituted acetic acid) ester of a polyhydric alcohol.

DONALD J. LODER. WILBER. O. TEE'I'ERS. 

